Specialized mass spectrometry analyses are provided to the laboratory and to other collaborating units. The emphasis of this work is split between identification of trace organic compounds isolated from biological sources and the mass spectrometry of biopolymers (e.g. proteins). A very close working relationship is maintained with the Laboratory of Biophysical Chemistry, NHLBI, and, with the move into macromolecule mass spectrometry, has been extended to pursue and develop techniques in this area. A major portion of this projects effort has been devoted to the development of methods for handling, digesting and mass analyzing biopolymers. An electrospray source was attached to the JEOL SX102 instrument, and this is now producing mass spectra of macromolecules. A capillary zone electrophoresis instrument was obtained and is being used to study digestion methods on-line to establish the optimum stopping points for protein cutting methods. This has also been interfaced to the electrospray source in a preliminary fashion where its separation efficiency far surpasses that of traditional HPLC methods. As part of the macromolecule collaboration, LBC, NHLBI, has installed a mass spectrometer especially set up for sequencing of protein digests. In the small molecule area, collaborative interest has continued in the identification of biologically active natural products, especially those of interest in AIDS research and treatment; several plasma drug level studies have been completed in collaboration with NINCDS. Samples analyzed derive from many facilities and researchers.